Effect Of L-thyroxine Therapy Research Articles

Thyroid Peroxidase Antibody among Hypothyroid Patients and Clinical and Biochemical Response to L-Thyroxine Replacement Therapy

This study was carried out in the Department of Medicine, Rajshahi Medical College, in 2006-2007 to study the thyroid peroxidase (TPO) antibody level among hypothyroid patients and to find out the effects of L-thyroxine therapy in TPO-antibody titer. After thorough physical examination and relevant investigations, 100 patients of hypothyroidism were enrolled in this study. The selected patients were given L-thyroxine replacement therapy at a dose of 50-150 microgram/d. Before starting L-thyroxine, serum was collected from all patients to estimate anti TPO-antibody level. All patients were followed-up after 12-28 weeks of full dose of L-thyroxine therapy. Patients with high TPO-Abs at baseline, only 17.6% turned into euthyroid (based on composite clinical score), whereas about 42% of the patients who did not have high TPO-Abs became euthyroid suggesting that patients with high TPO Abs may show significantly poor response to treatment compared to the patients without high TPO Abs (p < 0.001). Patients with high TPO-Ab titers also showed a decreased biochemical response (TSH values) compared to the patients without high TPO-Ab positive patients. So, TPO-Ab plays a significant role in causation of the disease and is also associated with poor treatment response with L-thyroxine replacement therapy.
 TAJ 2018; 31(2): 45-49

Improvement of Insulin Resistance and Cardiovascular Risk Factors with Treatment of Subclinical Hypothyroidism in Patients with Autoimmune Thyroiditis

Introduction: Subclinical hypothyroidism (SCH) seems to be associated with increase in cardiovascular risk factors and insulin resistance. The effect of the treatment of SCH with L-thyroxine on cardiovascular profile is not yet clear. Methods: We evaluated the effects of L-thyroxine therapy in 120 patients (mean age 45.7 ± 12.2 years, 80 women) with SCH due to autoimmune thyroiditis that had no prior treatment for thyroid or cardiovascular disease. The treatment was titrated to TSH levels between 0.4 and 4.0mIU/L. The laboratory data obtained, before and at least 6 months after thyroid function normalization, included thyroid function, antithyroid antibodies, lipid profile, and HOMA-IR (Homeostasis Model Assessment for insulin resistance), HISI (Hepatic Insulin Sensitivity Index), and IGI (Insulinogenic Index). Statistical analysis was performed with Mann-Whitney test, and Spearman’s correlation coefficient. Results: After treatment L-thyroxine, we observed a significant decrease of TSH (6.43±0.53 to 1.23±0.42 mIU/L, p=0.03) and a significant increase of fT4 (0.74±0.12 to 1.25±0.14 ng/mL, p<0.05). We also observed a decrease of LDL (116.1±34.2 to 91.2±16.3 mg/dL, p<0.01) and Lp(a) (32.0 ±19.1 mg/dL to 21.4±18.1 mg/dl, p<0,01). HDL and Apo A1 increased significantly after treatment (45.2±15.2 to 58.5±18.1 mg/dL, p <0.01; 124.5±43.3 vs. 136.5±56.4 mg/dL, p<0.01, respectively). Treatment with L-thyroxine significantly reduced HOMA-IR (0.24±0.17 to 0.17±0.10, p=0.03) and HISI (334.9±92.9 to 703.8±97.1, p=0.02). At baseline, TSH was positively correlated with total cholesterol (r=0.38, p=0.01), LDL (r=0.38, p=0.01), TG (r=0.28, p=0.01) and IGI (r=0.22, p=0.05). FT3 was negatively correlated with Lp(a) (r =-0.41, p=0.04). Conclusions: The treatment of SCH in patients with autoimmune thyroiditis is associated with a significant improvement of insulin resistance and cardiovascular risk. Disclosure C. Neves: None. S.C. Oliveira: None. J. Neves: None. M.G. Pereira: None. O. Sokhatska: None. A. Oliveira: None. J. Medina: None. L. Delgado: None. D.M. Carvalho: None.

Risk of Depression, Chronic Morbidities, and l-Thyroxine Treatment in Hashimoto Thyroiditis in Taiwan: A Nationwide Cohort Study.

The aim of this study was to evaluate the risk of depression in and effect of l-thyroxine therapy on patients with Hashimoto thyroiditis (HT) in Taiwan.In this retrospective, nationwide cohort study, we retrieved data from the Longitudinal Health Insurance Database 2000. We collected data of 1220 patients with HT and 4880 patients without HT for the period 2000 to 2011. The mean follow-up period for the HT cohort was 5.77 years. Univariate and multivariate Cox proportional hazards regression models were used to estimate the risk of depression in the HT cohort.In the HT cohort, 89.6% of the patients were women. Compared with the non-HT cohort, the HT cohort exhibited a higher prevalence of diabetes mellitus, hyperlipidemia, and coronary artery disease. Furthermore, the HT cohort showed a higher overall incidence of depression compared with the non-HT cohort (8.67 and 5.49 per 1000 person-year; crude hazard ratio [HR] = 1.58, 95% confidence interval [CI] = 1.18–2.13). The risk of depression decreased after administration of l-thyroxine treatment for more than 1 year (adjusted HR = 1.02; 95% CI = 0.66–1.59).In Taiwan, the overall incidence of depression was greater in the young HT cohort. l-thyroxine treatment reduced the risk of depression.

Delayed Closure of the Ductus Arteriosus in Term Newborns with Congenital Hypothyroidism: Effect of l-Thyroxine Therapy

Congenital hypothyroidism is associated with an increased incidence of congenital defects (15.6%), frequently involving the heart (5.8%). Only a few studies have evaluated the association between congenital hypothyroidism and patent ductus arteriosus. We report on two term newborns affected by thyroid agenesis and patent ductus arteriosus that closed after starting L: -thyroxine substitutive therapy. This association suggests a close relation between hypothyroidism and patent ductus arteriosus. Hypothyroidism should be considered in term infants with patent ductus arteriosus, because thyroid hormone production is among the prerequisites for postnatal ductal closure.

Delayed Closure of Ductus Arteriosus in Term Newborns with Congenital Hypothyroidism: Effect of l-Thyroxine Therapy

Congenital hypothyroidism is associated with increased incidence of congenital defects (15.6%), frequently involving the heart (5.8%). Only few studies have evaluated the association between congenital hypothyroidism and patent ductus arteriosus. We report on two term newborns affected by thyroid agenesis and patent ductus arteriosus that closed after starting L-thyroxine substitutive therapy. This association suggests a close relation between hypothyroidism and patent ductus arteriosus. Hypothyroidism should be considered in term infants with patent ductus arteriosus because thyroid hormone production is among the prerequisites for postnatal ductal closure.

Effect of l-thyroxine therapy on lipoprotein fractions in overt and subclinical hypothyroidism, with special reference to lipoprotein(a)

The effect of l-thyroxine therapy on lipoprotein fractions was assessed in 15 patients with overt hypothyroidism (14 women and one man aged 45 ± 3.9 years; thyrotropin [TSH]: mean ± SEM, 42 ± 6.5 mIU/L; range, 20.5 to 106.5) and 14 patients with subclinical hypothyroidism (13 women and one man aged 41 ± 4 years; TSH: mean ± SEM, 9.1 ± 1 mIU/L; range, 5.1 to 17.3). Fasting serum lipid levels were measured initially and 4 months after achievement of a euthyroid state with incremental l-thyroxine therapy (TSH: mean ± SEM, 1.8 ± 0.4 mIU/L; range, 0.3 to 4.9 for both groups). In the ovartly hypothyroid group, restoration of a euthyroid state was associated with a significant reduction in total cholesterol, and apo B. In the subclinically hypothyroid group, there was a significant reduction of only total cholesterol (199.6 ± 13.2 v 183.4 ± 11.6 mg/dL) and LDL-C (131.6 ± 8.4 v 114 ± 9.25 mg/dL). In contrast, lipoprotein(s) [Lp(a)] was unaffected by the incremental adjustment of l-thyroxine therapy in both groups (overt, 34.3 ± 8.8 v 35.6 ± 6.7 mg/dL; subclinical, 23.0 ± 8.6 v 29.4 ± 9.5 mg/dL). We conclude that restoration of a euthyroid state in patients with overt hypothyroidism has no significant effect on Lp(a) levels, and confirm that subclinical hypothyroidism is associated with a significant increase in LDL-C, known to have an atherogenic effect.

Live weight loss and its components in Romney ewes subjected to L-thyroxine therapy and a low plane of nutrition. Part II. Effects on some non-carcass components of live weight

1. The effects of l-thyroxine therapy and a low plane of nutrition on some of the non-carcass components of live weight in New Zealand Romney ewes were investigated.2. Thyroxine treatment significantly lowered the weight of the gastrointestinal tract contents. A low plane of nutrition and a longer total starvation immediately pre-slaughter had little effect in lowering the weight of the gastrointestinal contents. Alimentary tract ‘fill’ accounted for a group mean loss of live weight of up to 5 lb.3. Thyroxine treatment lowered the weight of the empty gastric tract, while a low plane of nutrition reduced the weight of both the empty gastric and intestinal tracts. The combined treatment effects accounted for a loss of up to 3 lb. in the weight of the empty gastrointestinal tract.4. Neither treatment significantly reduced the weight of the omental and mesenteric fat depots.5. The weight of the thyroid gland was unaffected by either treatment.6. A low plane of nutrition significantly reduced the weight of the liver, kidneys and the heart but had no effect on the weight of the spleen. Thyroxine therapy significantly reduced the weight of the liver and tended to increase the weight of the kidneys and the heart.